Freshwater Ecology Research Group
Riparian Management: Mackenzie Project (2008-2013)
Agriculture is an important land use in Canterbury and recent land use intensification has resulted in increased pressures on our waterways. Canterbury’s lowland waterways include modified streams as well as extensive drainage and water race networks. These waterways support productive use of land as well as being home to many native and mahinga kai freshwater species. Often these uses and values conflict. For example, high-intensity farming can increase sediment and nutrient inputs to waterways reducing the ability for freshwater fauna to thrive and degrading overall ecosystem health.
Our goal was to provide better scientific knowledge about what farmers and industry can do to improve waterway health in agricultural systems.
To do this, we investigated the source and fate of nutrients and sediment entering both rural and urban streams, examined the importance and influence of riparian plantings and identified patterns in water quality, stream communities, and in-stream processes (e.g., eutrophication) using a combination of spatially-extensive surveys and both in-stream and laboratory-based experiments.
|Small waterways strongly influence downstream water quality and stream health||Increased primary productivity leads to less biodiversity and altered energy flow in food webs|
|Riparian leaf litter can be added to increase denitrification and reduce in-stream nitrate levels||Riparian buffers along agricultural waterways in Canterbury are often narrow and dominated by exotic pasture grasses, weeds, shrubs and trees|
|Common macrophytes do not help solve nutrient problems||Excessive fine sediment cover (> 20%) results in loss of ecosystem services and sensitive taxa|
|Shade provided by riparian plantings in urban waterways improves water quality and biotic diversity||Accumulated fine sediment and slow water velocity impede the effectiveness of riparian management|
|Riparian shade mitigates eutrophication (increased primary production) by controlling aquatic weed growth||Active removal of fine sediment and channel narrowing can lead to dramatic improvements in waterway health and recovery of sensitive taxa|
Taken together, the findings from phase 1 suggest that to improve the effectiveness of riparian management and its effect on water quality, sediment and macrophytes, efforts should focus on:
1. “Fixing leaky plumbing” – by controlling the sources of sediments and nutrients into waterways and putting appropriate riparian management in the right spot;
2. “Starting at the top” – by targeting management tools and protection efforts on small waterways at the top of a catchment (or stream network);
3. Repairing the waterway – by applying rehabilitation tools to control aquatic weeds, remove sediment legacies, and enable lost species to recolonize
Peer reviewed articles
- Graham, S. E., O'Brien, J. M., Burrell, T. K., McIntosh, A. R. (2015) Aquatic macrophytes alter productivity-richness relationships in eutrophic stream food webs. Ecosphere 6:art89. doi: 10.1890/ES14-00341.1
- Renouf, K. and Harding, J.S. (2015). Characterising riparian buffer zones of an agriculturally modified landscape. New Zealand Journal of Marine and Freshwater Research 49(3): 323-332. doi:10.1080/00288330.2015.1013475
- Burrell, T.K., O’Brien, J .M., Graham, S.E., Simon, K.S., Harding, J.S. and McIntosh, A.R. (2014). Riparian shading mitigates stream eutrophication in agricultural catchments. Freshwater Science 33: 73-84.
- O’Brien, J. M., Lessard, J. L., Plew, D., Graham, S. E., and McIntosh, A. R. (2014) Aquatic macrophytes alter metabolism and nutrient cycling in lowland streams. Ecosystems 17: 405-417. doi: 10.1007/s10021-013-9730-8.
- Burdon, F. J., McIntosh, A. R., and Harding, J. S. (2013) Habitat loss drives threshold response of benthic invertebrate communities to deposited sediment in agricultural streams. Ecological Applications 23: 1036-1047.
- Greenwood, M. J., Harding, J. S., Niyogi, D. K. and McIntosh, A. R. (2012) Improving the effectiveness of riparian management for aquatic invertebrates in a degraded agricultural landscape: stream size and land-use legacies. Journal of Applied Ecology 49: 213–222.
- Graham, S.E. (2014). Mechanisms and mitigation of nutrient-induced food-web change in stream ecosystems. Unpublished PhD thesis, University of Canterbury.
- Burdon F.J. (2013). Impacts of sedimentation on the structure and functioning of agricultural stream communities. Unpublished PhD thesis, University of Canterbury.
- Moore, T.P. (2013) Nitrate-nitrogen effects on benthic invertebrate communities in streams of the Canterbury Plains Unpublished MSc thesis, University of Canterbury.
- Porter, E.M. (2013). Riparian management: investigating public perception and the effect of land-use, groundcover and rainfall on sediment retention Unpublished MSc thesis, University of Canterbury.
- Renouf K.A. (2013). Riparian buffer zones of the Canterbury agricultural landscape as nutrient filters. Unpublished MSc thesis, University of Canterbury.
- Roberts, K. (2012). Factors limiting invertebrate recovery during stream restoration. Unpublished MSc thesis, University of Canterbury.
- Burrell, T.K. (2011). Trophic state in Canterbury waterways. Unpublished MSc thesis, University of Canterbury.
- Franklin, H. (2010). Understanding variation in water quality using a riverscape perspective. Unpublished MSc thesis, University of Canterbury.
- Small waterways strongly influence downstream water quality and stream health (PDF 1.08MB)
- Excessive fine sediment cover (>20%) results in loss of ecosystem services and sensitive taxa (PDF 1.19MB)
- Shade provided by riparian plantings in urban waterways improves water quality and biotic diversity (PDF 966KB)
Information from other Organisations
- A guide to Managing waterways on Canterbury farms (PDF 713KB)
- Managing Waterways on Farms (PDF 4.6MB)
- Managing Riparian Zones (PDF 336KB)
- Review of Riparian Buffer Zone Effectiveness (PDF 1MB)
- National Map of Nitrate Leaching (PDF 1MB)
- Caring for streams of Canterbury Plains: a guide to riparian management (PDF 6MB)